Outdoor wood furnaces have been available for residential use since the early 1980’s using a fairly simple concept of transferring heat from one location to another. This is usually from the furnace outdoor location to a nearby house and / or building.  Additional uses include heating domestic hot water used for showering, laundry, dishwashers, and etc.   Some users even connect swimming pools and hot tubs to their outdoor wood furnace.    The process includes circulating water heated through an exterior contained unit (the outdoor wood furnace) into the house through use of a heat exchanger.   In most cases, your existing hydronic or HVAC system is used and/or modified for the outdoor furnace heat distribution.    Since this is usually an open non pressurized loop system,  the water which continues to be heated and circulated through the furnace is separate from your potable water.   The furnace is controlled to maintain a target temperature range which drafts a fire when the temperature gets low and then terminates the draft upon reaching a higher peak temperature.  

The single greatest benefit of an outdoor wood furnace is a significant reduction or elimination of heating costs. As many outdoor furnace owners live in rural areas, wood acquired from dead or dying trees is often plentiful and usually only requires a chainsaw and a little extra effort to prepare for the heating season.  The next benefit is elimination of potential fire hazards, smoke smell, and mess of alternative heating options. Positioning the furnace in an exterior location is even safer than conventional heating sources such as fuel oil, natural gas, and electric.    Most homeowners recognize lower insurance premiums than homes with conventional wood burners and fireplaces.   Unlke conventional heating systems which require you to still purchase fuel, natural gas, propane, electric, etc. after your initial investment, an outdoor furnace investment is covered in an average of 3 years without any additional future cost other than cutting firewood and routine maintenance.